Socal Edison requires sand for one conduit. Two conduits are to be partially encased, conduits laying on sand, concrete poured on top of them. 3-4 conduits are to be fully encased, concrete all around them.

I forget when you need to start seperating them, but I know if you have 8 conduits you have to split them into seperate trenches.

SCE did not require anything special for Secondary Feeders, unless the Soil is very "Rocky", then they want some Sand.

I have the currently used "ESR" Manual from SCE (Electrical Service Requirements Manual), which I use for assistance in designs/engineering projects. If needed, let me know some specifics and I can reply with quotes from the ESR.Although it may not be exactly what your PoCo would specify, it might be somewhat relavent - just for an idea.

SCE did not require anything special for Secondary Feeders, unless the Soil is very "Rocky", then they want some Sand.

Scott35, in all the work we have done for Edison the secondaries have the same requirements as primaries. This usually means more work on the secondaries on our projects since there are usually multiple conduits which require encasement. While the primary usually is a single conduit requiring just sand.